Photoelastic Behavior of Liquid Crystalline Polymer Networks

Abstract

The linkage of low molar mass liquid crystals as side groups to a polymer main chain leads to a new class of substances which are important with respect to theoretical aspects as well as future technological application. They combine the liquid crystalline (LC) behavior with specific polymer properties 1,2. To get an almost complete decoupling of the motions of the polymer backbone and the mesogenic moieties they are connected by covalent bonds to the backbone by a flexible spacer. Investigations on the state of order of LC-polymers compared with the state of order of low molar mass LCs indicate that the linkage to the polymer chain by sufficiently long flexible spacers does not essentially influence the state of order 3.. Under these conditions the mesogenic side chains can spontaneously form an anisotropic orientation and thus build up a LC phase 4.. There are some indications that the conformation of the polymer chain is changed by the formation of the anisotropic LC phase. Instead of a statistical coil conformation it rather has to be assumed that the coil is more or less anisotropically deformed.